Pharmacologic studies of cardiac ANS control using sequential blockade and atropine (muscarinic cholinergic anatagonist) followed by esmolol (cardioselective beta-1 adrenergic antagonist) and defining parasympathetic control (PC) and sympathetic control (SC) as the magnitude of the attendant sequential changes in mean R-R (or interbeat) interval in msec. These pharmacological studies have confirmed our early spectral analysis HRV findings and extended them into the sympathetic domain, and suggest that both arms of the cardiac ANS change as weight and caloric intake are perturbed from their usual levels.